Scientific Forecaster Discussion

NWS Discussion
			
				

Area forecast discussion 
National Weather Service Des Moines Iowa 
638 PM CDT Thursday may 23 2013 


Short term.../tonight /... 
issued at 310 PM CDT Thursday may 23 2013 


Little of concern tonight with Iowa between High Plains ridge and 
departing Great Lakes trough. Although skies will be clear with 
light winds as surface high pressure crosses the upper MS 
valley...overnight lows should only dip into the upper 30s northeast 
keeping frost concerns at Bay. 


Long term.../Friday through Thursday/... 
issued at 310 PM CDT Thursday may 23 2013 


Active period setting up for the Holiday weekend into next 
week...with main issued surrounding chances for thunderstorms and 
potential for heavy rain. High pressure initially over the area 
Friday with dry conditions expected...however the surface high quickly 
shoves east with warm air advection and moisture advection back into western Iowa 
by late Friday afternoon. This will allow for some potential 
thunderstorms across western Iowa late in the afternoon. Chances for 
thunderstorms to become more widespread across the County Warning Area as weak 
shortwaves push eastward through the upper level ridge expected to 
remain in place through the weekend. Thunderstorm chances will 
remain with the climatological favored times in this type of 
pattern...mainly in the evening to overnight hours and lingering 
into the morning. With the extended chances for thunderstorms and 
rainfall...flash flooding and river flooding becomes a concern. 
Moisture transport oriented into Iowa for much of the Holiday 
weekend...precipitable waters  well above average increasing into the 1.3 to 1.5 
inch range...and fz level quite high suggesting efficient rain 
production through the weekend. Widespread rainfall amounts of 1 
to 2 inches with locally higher amounts are possible through the 
Holiday weekend. Severe parameters not that great...so widespread 
severe weather is not anticipated. 


Upper level ridge begins to shift east slightly and dampen 
some...with a surface warm front expected to lift northward through the 
state Tuesday. An upper level closed low digs into the Desert 
Southwest with impulses ejecting out ahead of the main system 
through the region. With the warm front stalling out across the County Warning Area 
Tuesday into Wednesday...and the energy lifting through the 
area...thunderstorm chances continue into next week across the area. 
Warmer temperatures also expected with the warm front lifting 
north...with much of the area returning to 70s and 80s by the middle 
of next week. 


&& 


Aviation...24/00z 
issued at 637 PM CDT Thursday may 23 2013 


Few concerns this period. High remains over the area through 
overnight hours as trough of low pressure over the Western Plains 
drifts east Friday. In response some high and middle level clouds 
will increase for kfod and kdsm 15-22z. Winds will increase from 
the south southeast at kfod and kdsm as well from 14z-00z with 
gusts to 20kt after 16-20z. None weather until system arrives after 00z with 
nocturnal thunder likely becoming more problematic for ceilings and visibilities 
after 04z...and will include more details next update. 


&& 


Dmx watches/warnings/advisories... 
none. 
&& 


$$ 


Short term...small 
long term...beerends 
aviation...rev